In the above-identified application, Ser. No. 07/115,245, filed Oct. 30, 1987, entitled; TRANSCEIVER SYSTEM FOR COMMUNICATION OVER WIRE LAID ALONG THE PATH OF GUIDED VEHICLES we disclosed how to connect a modem and a loop driver to a typical floor loop then in use for guided vehicles.
We have discovered that such floor loops typically exhibit one or more null positions at which the signals sent from the host modem is so low (or non-existent) that communications is impossible with the guided vehicle.
According to the prior art, the automated guided vehicle floor loop is a current loop conductor. That is, the two ends of the wire of the floor loop are connected to a loop driver and, if used, to a communications modem. In fact, the floor loop is better viewed as a transmission line sitting above a ground plane, surrounded by a dielectric which generates radiation losses and which also slows the propagation velocity below that of a simple conductor.
The recognition of this more accurate model has lead us to design our equipment differently than the prior art.